The present invention pertains to strapping machine weld head vibrator assemblies. More particularly, the present invention pertains to vibrator assemblies having a simplified, one-link design.
Strapping machines are well known in the art. Typically these machines are used for securing straps around loads. One type of strapper is used with a plastic or polymeric strap and is a stationary arrangement in which the strapper is included as part of an overall manufacturing or packaging system.
A typical strapper includes a frame to which various components are mounted. A chute is mounted to the frame through which the strapping material is fed around a load. A strapping head and a drive or feed mechanism are mounted to the frame. The strapping material is fed from a source, by the feed assembly, through the strapping head. The strapping material traverses around the chute and back to the strapping head.
The strapping or welding head provides a number of functions. The strapping head grips the strap during the course of a strapping operation and cuts the strap from a strap source or supply. In addition, the strapping head includes a sealer to seal an overlying course of strapping material onto itself. This seal is commonly referred to as a weld and is effected by heating one course of the strap by use of a vibrating element.
Known strapping heads include a body and an anvil between which the courses of strap materials traverse during a strapping operation and between which the strapping material courses are held during the welding operation. The anvil is maintained rigid and a weld pad is brought into contact and applies pressure against the strap. The pad is carried by an element that oscillates or vibrates (and oscillates the pad) thus creating friction and heat to effect the weld.
The drive for the vibrating element and pad is typically a motor or other rotational drive. In order to impart vibrational motion to the element, the rotational motion of the motor must be transferred to linear motion. Known strappers include complex linkages or eccentric shaft arrangements having open (elongated) slots. While these arrangements function well for their intended purposes (and particularly the eccentric arrangement), there are drawbacks. For example, as with any complex linkage, problems can occur at the linkage joints. As to the eccentric configurations, there is always the potential for debris to accumulate in the elongated slot (that receives the eccentric shaft). Such an eccentric-containing configuration is disclosed in Gerhart et al., U.S. Pat. No. 6,532,722.
Accordingly, there exists a need for a simplified assembly for a welding or strapping head weld pad. Desirably, such an assembly eliminates the need for complex linkages and open regions otherwise required to transfer rotational motion into linear motion. More desirably, such an assembly is of a compact design and readily permits removal for tool maintenance and inspection.